All eBooks allow users to adjust the font size of the text that is being read. At the largest setting, this can make eBook text even larger than the text in physical large print books.
A computer screen can always be adjusted for contrast and brightness to help the visually impaired see text better. If using an e-reader, the contrast options depend on the model: iPads, Sony Readers and Nooks all allow the screen contrast to be adjusted.
Free computer software that can convert text on a computer screen to speech is widely available. The Bookshare program offers two DAISY reader software options for the visually impaired. E-readers are more limited in their text to speech capabilities, although both the Kindle and the iPad offer functions that read text aloud.